Croduino Nova pins 2, 4, and 5 behaving unusually

TECHNICAL SUPPORT NULA Development Boards
1

Customer:

I was investigating some unusual behavior with a DHT11 sensor and discovered a strange issue with the digital inputs/outputs. Pins 4 and 5 appear to be swapped - digitalWrite/digitalRead commands on pin 4 affect pin 5 and vice versa. The labels on the board and pinout appear to be reversed. I’ve included a test program where I select an output and measure it with a voltmeter every 5 seconds to verify this. Pin D2 is always at 3.3V even though digitalWrite/digitalRead show the correct values in the Serial monitor. All other pins work fine. I suspect this is why the DHT11 wasn’t working. I’m wondering if this is a general issue with all Croduino Nova boards or just mine, particularly regarding pins 4 and 5. Pin 2 might be defective or requires some specific setup, though I haven’t tested it in INPUT mode yet.

Original message (Croatian)

[name removed] bok!

Malo mi je bila neobična situacija u vezi DHT11 senzora pa sam išao gledati digitalne ulaze/izlaze i došao sam do neobičnog ponašanja.

Najkraće rečeno pinovi 4 i 5 su zamijenjeni. Naredbe digitalRead/Write od 4-ke djeluju na 5-cu i obratno. Kao da su oznake na pločici i pinout-u zamijenjene. U prilogu je program da vidiš kako sam testirao. Odabereš izlaz a on svakih 5s mijenja stanje a napon sam mjerio voltmetrom.

Drugi problem je pin D2 koji je uvijek 3,3V mada digitalRead/Write ispravno pokazuju u Serial monitoru. Ostali ponovi su ok.

Pretpostavljam da su to razlozi zašto DHT11 nije radio.

Ne znam je li to slučaj samo kod mene ili se radi o generalnom ponašanju Nove (prvenstveno mislim na pinove 4 i 5). Pin 2 je možda neispravan ili je po nečemu specifičan pa nešto moram programski uključiti/isključiti. Doduše, nisam ga provjerio u pinMode(INPUT) ali budem pa javim.

Attachment omitted in migration: N_IOtest_Nova.ino

Originally submitted via email support on 29 August 2017. Migrated to the forum for community visibility.

2

Soldered Support:

You’re correct about pins 4 and 5 - that’s a known oversight. Regarding pin 2, it has a pull-up resistor on it, but it should still work when using digitalWrite. However, it’s possible it behaves differently since this is a microcontroller with very little documentation and its internal architecture is unknown to us. In any case, I tested it and got the same result. The pull-up resistor must be there or it wouldn’t boot into flash mode without it. To summarize: pin 2 behaves this way generally, and pins 4 and 5 are my fault - I’ll note it on the web and fix it in the next version.

Original message (Croatian)

[name removed]

u pravu si za pinove 4 i 5 - poznat nam je taj previd.

Što se tiče pina br.2., on na sebi ima pull up otpornik, ali bi opet trebao raditi kada se koristiti digitalWrite. IAKO, moguće je da je drukčije budući da se radi o mikrokontroleru s jako malo dokumentacije i nepoznata nam je njegova unutarnja građa.

U svakom slučaju, ja sam isprobao i dobivam isti rezultat. Pull-up otpornik mora biti tamo jer se ne bi boot-ao u flash mode da ga nema.

Da zaključimo: radi se o generalnom ponašanju na pinu 2, a za pinove 4 i 5 sam ja kriv :slight_smile: - napomenut ću na webu i u idućoj verziji ispraviti.